Wanting as much credible information, and proof, as possible, before acting, is not being sceptical, it is using critical thinking. If there are credible tests that show that the claims of the promoters of this product are correct, then I would accept that. As of now, I have not seen any credible evidence to support the claims.
If "John's" dentist were to run some tests, and identified him/herself, and published those tests, so that they could be verified, repeated and reviewed, then I see no reason not to trust the results. "John" could remain anonymous, as most test subjects are not required to be identified by their actual names. It is also important to know who is funding the tests, and any conflict of interest that may occur. (for example, I do not trust the results of tests, done by drug companies, on their own products, unless these results can be repeated independently).
The same applies if you decided to run some tests.
Its not a matter of satisfying me in particular, its a matter of giving as much proof as possible, to ensure credibility of those performing the tests.
It can be verified that JH actually exists, and it has also been verified that he has lied about his qualifications and experiences, and he lies about the efficacy of the products he promotes. This paints him as a person that is not credible, and makes whatever statements he makes highly suspect.
If people choose to ingest a chemical, based on anonymous internet testimonies, or the word of someone as completely discredited as JH, that is their choice. They should also be aware that if they harm themselves, they will have no-one to blame but themselves.